Using pervasive computing, Want attempts to relate a variety of concerns about energy conservation and carbon dioxide (CO₂) emissions.

As is customary in energy and emissions analysis, Want debates the life cycle emissions and consumption balance, when upstream and downstream manufacturing, transportation, processing, installation, and repairs are all taken into account. Clearly, the balance may not always be as positive as when savings from the finished functional component or system alone are considered. Want discusses context-aware systems with sensing and actuation, green homes with passive heating and photovoltaics, the Toyota Prius hybrid car and kinetic energy restoration, and his own experience with X10 light switches.

Unfortunately, Want fails to note that the spreading energy efficient certification of electronic components and systems takes the life cycle view and involves extensive data collection. Also, energy savings do not always lead to emissions savings, as the processes involved have nonlinearities in their CO₂ emissions-to-energy-consumption profiles, both at the manufacturing stage and in operations.

Want claims that, for components that have already been produced in series for a while, “the energy production costs ... are already amortized over many products”; this fails to address the total energy life cycle balance of all of these components taken together. The information and communication technologies (ICT) Action IC0804 (http://www.cost804.org), for example, has mapped out in much more detail the subprocesses involved in positive and negative life cycle energy savings from embedded and distributed computing.